Vegetable oils are utilized not only in the food industry, but also increasingly in the chemical industry. The utility of any particular oil depends upon chemical and physico-chemical properties of the oil, which are determined by the composition of the constituent fatty acids. Plant oils are often modified to meet industry specifications. Such modification of vegetable oil has typically been achieved by chemical means (fractionation, interesterification, hydrogenation, or other chemical derivatization), but genetic means (plant breeding, mutagenesis and genetic engineering) are increasingly being used to provide novel oil feedstocks.
One class of particular interest is the class of triacylglycerols containing sn-3-acetyl glycerides (1,2-diacyl-3-acetins). These unusual triacylglycerols have an acetyl group at their sn-3 position. The occurrence and structural characterization of sn-3-acetyl glycerides in seed oils was first reported by Kleiman et al. (1967) (Lipids 2:473-478). Unlike most triacylglycerols, sn-3-acetyl glycerides exhibit strong optical activity. They are found at high levels in Euonymus species, representing up to 98% of the total triacylglycerols in the seed oil, and are also found in varying amounts in some other plant species. In the Euonymus sn-3-acetyl glycerides, the sn-1 and sn-2 positions are esterified with common long-chain fatty acids, predominantly palmitate, oleate and linoleate.
Currently, there are no commercial sources of oils rich in sn-3-acetyl glycerides. Moreover, plants with high levels of sn-3-acetyl glycerides are not grown commercially. In fact, the biosynthesis of these novel glycerides has only recently been investigated.
There are several triacylglycerol producing reactions that undergo sn-3 acylation or transacylation reactions, including two classes of DAGAT genes, and a phospholipid:diacylglycerol acyltransferase. One class of DAGAT genes has been isolated and expressed from Arabidopsis based upon their homology to the mammalian DAGAT gene, and more broadly to acyl-CoA:cholesterol acyltransferase (ACAT)-like genes, and by mapping of the gene corresponding to a mutation. A second class of DAGAT genes can be identified based upon homology to a DAGAT first purified from a fungus, Mortierella ramanniana. However, a gene has not been identified, much less isolated and expressed, from an organism that exhibits a unique triacylglycerol such as is found in seed oils of the genus Euonymus. 
Moreover, the availability of a DAGAT with acetyl-CoA:sn-1,2-diacylglycerol acyltransferase activity would allow novel triacylglycerol structures to be produced; such novel triacylglycerol molecules could by synthesized in vitro or in vivo. The presence of an acetyl group rather than a long-chain fatty acid esterified at one or more, but not all, of the positions on the glycerol backbone will reduce the calorific value of the oil while not interfering with its functionality in foods. Also, an oil such as olive oil or high oleic oils, or castor oil, which all contain a large amount of trifunctional triacylglycerols, such as triolein or triricinolein, would easily be converted to bifunctional oils if an acetyl group replaced the fatty acid at the sn-3 position. Such oils would have different industrial applications than their trifunctional counterparts. For example, a bifunctional triacylglycerol would produce linear (thermoplastic) polymers whereas a trifunctional triacylglycerol would produce cross-linked (thermosetting) polymers.
Therefore, it would be desirable to be able to generate vegetable oils with high amounts of acetyl glycerides, and in particular sn-3-acetyl glycerides. One route is by identifying and isolating a plant gene that is capable of synthesizing acetyl glycerides. Such a gene could then be used to transform oil crop plants. Identification of such a gene could also be used to synthesize novel acetyl glycerides that do not exist naturally.